Definition - What does Two-Tier Client/Server mean?
A two-tier client/server is a type of multi-tier computing architecture in which an entire application is distributed as two distinct layers or tiers. It divides the application logic, data and processing between client and server devices.
Techopedia explains Two-Tier Client/Server
For example, the core application and data are installed at a central server. One or more client devices uses its client-end application to request data or processes from the server. The server sends the required data or performs a process to fulfill the query. In another two-tier client/server instance, such as a data backup architecture, the application access and logic may be with the client device, whereas the server stores and provides the core data.